A secondary button cell battery that is particularly suited for use in
hearing aid appliances, and an associated charging station. Recharging is
accomplished without direct conductive connection between the source of
the energy and either the battery or its appliance. Radio frequency
energy is harvested in an enclosed chamber in a charging station and
applied to the recharging of the button cell. Such energy is harvested by
the use of one or more energy harvesting diodes connected in parallel
with the battery. Multiple diodes connected in parallel or serial may be
used to adjust charging current or voltage or both. Charge control is
provided by directly or indirectly detecting the level of charge on the
cell. Where the associated appliance is a hearing aid, the charge level
detection may be accomplished acoustically by determining the
characteristics of the sound emitted by the hearing aid, and charging is
accomplished with the cell within the hearing aid appliance.